An optical sensing unit is mainly adopted by an existing touch panel to determine a touch position. Generally, a mainstream optical sensing unit includes two thin film transistors (TFTs), i.e., a Photo TFT and a Readout TFT, and one storage capacitor. When the optical sensing unit is exposed to a light beam, a leakage current is always generated by the Photo TFT and stored in the storage capacitor. In each Photo period, the Readout TFT is turned on once, so as to read out an electric signal stored in the storage capacitor. A state of the Photo TFT may be determined in accordance with the electric signal read out by the Readout TFT, so as to determine the touch position.
The Photo TFT is required to receive an ambient light beam, so it must be exposed to the ambient light beam. However, the Readout TFT cannot be exposed to the ambient light beam, otherwise an undesired photoelectric current will be generated by the Readout TFT, and thereby the electric signal read out by the Readout TFT will be adversely affected. Hence, for the touch panel, it is required to provide a black matrix to shield an active layer of the Readout TFT, so as to prevent the active layer of the Readout TFT from being exposed to the ambient light beam. When the optical sensing unit is integrated into a display panel, a black matrix of the display panel itself may be used to shield the active layer of the Readout TFT. However, when the optical sensing unit is not integrated into the display panel, it is required to provide an additional black matrix to shield the active layer thereof, which thus results in a complex process and an increase in the production cost.